Some images couldn't display On N8(a qt and qml game app by qt creator and qt 4.7.4)

hi, now i developed a game application by qml and qt, there are a lot of jpg images in app.
but many images couldn't display immediately on N8， but if i run lock screen key or press home key On N8 and restore, these images will display immediately successful. I try many ways to reslve the problem(for example, set up "asynchronous: false; cache:false" in qml file and in image element， or in qt part, invoke update(), repaint.... but all these ways not work)
My qt version is 4.7.4.

so, now i want to display these images successful on N8,
Please give some good advice, thank you very much!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1